hi just a quick question or 2

Im data logging my maf sensor and i have managed to get some readings and convert them to a chart in excel so now i want to get a proper reading of my maf sensor as i suspect it maybe faulty plus im enjoying having a play with vag.com

I know i have to get the rev range between 2500 and 3500 in 4 or 5 th gear but do i take the reading at full throttle or at a constant speed/load.

It not easy when the cars mapped as you dont get a very big window to start stop it lol

Also what would indicate the maf was faulty a higher reading than specified or lower on the actual line of the graph?

Advise please

Full throttle in either 3rd or 4th gear and up to where the engine produces most power (hp). With gasoline engines this is usually close to the red line, with diesels its indeed mostly around 3500 RPM.

and any idea what reading will indicate a faulty maf sensor?

Which engine do you have?

the maximum reading will be at the rpm where you get the highest torque

the maximum reading will be at the rpm where you get the highest torque

On a diesel where the readings are in mg / stroke, that's likely true.

But on a gasoline ("petrol") motor where the readings are in g/sec, that's not the case. The maximum reading will be at the RPM where the engine produces the most horsepower. On most, that will be between 5500 and 6000, or just shy the redline.

-Uwe-

err... i assumed it was a diesel because the picture of the car in his avatar is a fabia vrs

yes its a vrs sorry should have pointd this out at beginning. I just wanted to know what the difference will be between actual and what it should be when the maf is correct and when its on way out, or even faulty so i can compare when i do the test in the week.

Regards

i cant remember what the reading is on those maf sensors, but iirc the ouptup should be about 3.3v

At idle the 3.3 may fit, but IMHO not under load.

Anyway, if you read the MAF under load with VAG-COM make sure the graph is steady and doesn "jump" too much. The value should be at least 850 mg/str.